JPH09184817A - Gas-detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas-detecting apparatus which can be manufactured in a more simplified assembling method, efficiently detect a harmful gas substance existing in a vehicle or outside a room and ventilate a circulating air. SOLUTION: The gas-detecting apparatus includes a case 2 wherein a sensor 21 used in an electric measurement device is installed. The sensor 21 coming in touch with a circulating air through an air path 52 is attached to a connecting part 18 of an electric circuit board 10 and projected to a chamber 38 from the case 2. The chamber 38 has a pair of holes 44 and is set on a case cover 24. The pair of holes 44 of the chamber 38 have a pair of corresponding filters 46. The connecting part 18 is covered with a case cap 50 having the air path 52 formed between an inner wall 58a and an outer wall 58b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas detection device for detecting harmful gas substances existing in a vehicle or outdoors, and more particularly to a gas detection device which can be manufactured by a more simplified assembling method and which can effectively remove harmful gas substances The present invention relates to a gas detection device that can detect airflow and ventilate the surrounding air.

[0002]

2. Description of the Related Art In the case of a ventilation device for a vehicle, one sensor element for detecting a harmful gas substance in the surrounding air and controlling a ventilation operation is disclosed in Patent Application DE. Pat. No. 44 145
No. 94. As such a sensor element, a zinc oxide sensor element has been adopted. The sensor element uses a special measurement technique to detect gasoline gas or diesel gas generated from a gasoline vehicle or a diesel vehicle.

If the detected gas level exceeds a predetermined reference value, a ventilator incorporating such a sensor element is automatically enabled to ventilate the surrounding air. Such a ventilation device is widely used in various luxury vehicles. For example,
The BM (BMW) Company uses a gas detector with a sensor element mounted inside a capsule covered with a metal grid. Here, the capsule is placed behind the wool filter and the surrounding air is in contact with the sensor element through the wool filter. However, in such a conventional ventilation device, there is a problem in that the solid fine particles stick around the sensor element, thereby lowering the sensitivity of the sensor.

On the other hand, the gas detection device manufactured by Boach is operated using two sensor elements for detecting gasoline gas and diesel gas separately. Here, each sensor element is covered with a Teflon tube that allows gas to pass therethrough. The Teflon tube is inserted and attached in a metal tube provided with a plurality of air passages.
Furthermore, these tubes are fixed in a case with an electrical measuring device which produces a control signal for controlling the ventilation device.

However, the above-described conventional gas detection device has the disadvantage that the structure of the device becomes more complicated and the manufacturing cost increases considerably because it uses two sensor elements.

[0006]

SUMMARY OF THE INVENTION Therefore, the main object of the present invention is to be manufactured by a more simplified assembly method and to effectively detect harmful gaseous substances present in the vehicle or the exterior. It is to provide a gas detection device that can ventilate ambient air.

[0007]

In order to achieve the above object, according to a preferred embodiment of the present invention, a chamber in which a sensor element is to be incorporated is mounted on a case cover to make the apparatus compact and robust. Structure is possible. In such a device structure, the sensor element is, for example, stably protected from impacts and harmful substances and can be easily contacted with the surrounding air. Further, in the gas detection device of the present invention, the sensor element is attached to the sub circuit board, and soldering is used to realize the connection between the sub circuit board and the main circuit board. In this case, if the connection part is formed as part of the circuit board, the sensor element is mounted on the connection part of the circuit board, so as to realize an electrical connection between the sensor element and the electrical measuring device.

In a preferred embodiment of the present invention, the main circuit board is provided in the case, and the sensor element is projected from the case so as to be inserted into the case cover when the case cover is covered on the case. Then, the case is filled with the coagulating liquid synthetic resin through one of a pair of holes formed on the case cover, so that the case cover is firmly fixed to the case. Thus, the inside of the case is sealed together with the main circuit board, and the sensor element provided in the chamber is placed outside the sealed case.

Further, the present invention uses a filter for sensor protection to protect the sensor element from fine particles in the air that may be introduced into the interior of the vehicle engine. This filter is formed in a laminated structure manufactured in the usual pad form. In the present invention, such filters are manufactured in sheet form using a composite material made of Gore-Tex fabric. Also, this thin plate filter is covered with a thin film Teflon as a second layer to block moisture,
Allow only gas to pass.

Therefore, in accordance with a preferred embodiment of the present invention, the thin plate filter is further covered with a metallic knit or woven fabric as a third layer. This third layer is used not only to physically protect the inner layer from the outside, but also to prevent erroneous operation that may occur due to temperature changes of the sensor element, regardless of harmful gas substances in the air. To elaborate,
Metal knitting has a thermal inertia
With a), it is used to isolate the sensor element heated to the driving temperature from the external temperature.

Moreover, such temperature barrier effect is enhanced by a firm connection between the metal braid layer and the other layers. Thin films (i.e., pads) made of a composite material such as the Teflon or GORE-TEX fabric described above are provided on the holes on both sides of the chamber so that they are placed on the edge of each hole by bonding. When mounting this metal knit on the chamber, it is preferable to bend one sheet of the metal knit into a U shape along the outer peripheral surface of the chamber. However, such an installation method results in the metal knit layer being pressed hard when the case cap is fixed on the case.

Further, the present invention has a band surrounding the chamber included in the case cover in order to tightly seal the case with respect to the chamber in which the sensor element is incorporated. The band is dipped in a coagulating liquid synthetic resin by a case cover. The connecting portion is projected from the case filled with the coagulating liquid synthetic resin. Therefore, the slight gap formed between the outer peripheral surface of the chamber and the case is
The solidifying liquid synthetic resin is sealed as it is solidified. In this case, by adjusting the height of the band,
Charge tolerance errors (ie horizontal height of coagulable liquid synthetic resin during sealing) are handled smoothly. As a result, the air gap present at the top of the case is kept constant at the predetermined volume by being separated from the chamber by the band. Further, the case cover is provided with a flange used to firmly fix the cover to the inner surface of the case. The flange advances along the inner wall of the case to the inside thereof and is surrounded by the supplied coagulating liquid synthetic resin. Thus, the flange of the case cover is fixed to the case by solidifying the coagulating liquid synthetic resin. Further, since the pair of holes are formed on both sides of the chamber, the remaining air in the case will escape from the case when the coagulating liquid synthetic resin is filled in the case.

According to a preferred embodiment of the present invention, preferably ambient air is circulated around the sensor element contained in the chamber, the sensor element being subjected to a sudden impact, a propellant emitted from the engine mount of the vehicle. A case cap is provided so as to be protected from. Due to the labyrinthine air passage inside the case cap, the present invention ensures that the ambient air is circulated evenly through the air passage around the sensor element and that the propellant does not contact the sensor element. To do. Moreover, such an air passage serves to provide a separation between the inside and the outside of the chamber during temperature changes. The air passage may be formed by making the inner structure of the case cap into a double-walled structure (ie, an inner wall and an outer wall). Here, the inner wall and the outer wall are connected to each other through a connection frame.

More specifically, the air passage is a space formed between the inner wall and the outer wall of the case cap, and each wall is provided with a plurality of slots displaced from each other. When the case cap is mounted on the cover, the internal structure of the inner wall is
It is formed so that a connection is made between the inside of the case cap and the inner surface of the chamber. On the injection surface of the coagulating liquid synthetic resin into the case, it is preferable that the frames formed on the inner wall and the outer wall are formed in the axial direction and the slots are formed in the width direction. The case, the case cover and the case cap may be mainly made of synthetic resin by using an injection molding technique.

Furthermore, the present invention employs a zinc oxide sensor in which the sensor element can sense both reducing gas and oxidizing gas.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will now be described in detail with reference to the drawings. Referring to FIG. 1, there is shown a schematic block diagram of a gas detection device according to the present invention. This gas detection device has a circuit board 10,
A cable 12 for transferring data, a pair of plates 4, 6 for mounting the case at an appropriate position on the vehicle
And a sensor element 21.

The circuit board 10 is composed of a plurality of electric elements and is provided in the case 2. More specifically, the circuit board 10 is inserted along the side guide wire 8 into the case 2 until the circuit board 10 reaches the stopper 16, and is connected to the cable 12 to be attached. Here, Case 2 is
It is connected to a controller (not shown) that controls a ventilation device or an air conditioning device of the vehicle. In this case, the cable 12 is firmly fixed by the cable support member 14 and maintained in a stable state. The connecting portion 18 is provided with a sensor attaching portion 20 for attaching the four conductive lines 22 and the sensor element 21, and protrudes from the case 2. The conductive line 22 is connected to the sensor element 21, the electrical element and the thermal component to be used to obtain the desired driving temperature. Furthermore, the connecting portion 18 is electrically and mechanically connected to the circuit board 10, and may be a small sensor circuit board. Also, the connection 18 can be part of the electrical circuit board.

As shown in FIG. 2, the flange 26 of the case cover 24 is inserted into the case 2 to close the open portion of the case 2 until the edge portion 28 of the case cover 24 reaches the upper edge of the case 2. As shown in FIG. 2, the rectangular shielding member 30 is designed to be aligned with the connecting portion 18 and fit into the corresponding recess 32 of the case cover 24. Here, the recess 32 is formed by a band 34 protruding toward the inside of the case cover 24.

More specifically, the recess 32 includes the hole 36 and the band 3.
It is provided between the case 2 and the case cover 24 to provide a firm sealing between the case 2 and the case cover 24. The shield member 30 is used to adjust the tolerance, ie the air gap between the cross section of the connection 18 and the cross section of the hole 36 on the chamber 38. Further, the shield member 30 connects the connecting portion 18 to the circuit board 1
It functions to protect the sensor element 21 from soldering vapor generated when soldering to zero.

A plurality of 40 are provided on the flange 26 of the case cover 24. For this reason, when the case 2 is covered by the case cover 24 and the coagulating liquid synthetic resin is filled in the sealed case 2, the plurality of 40 are filled with the coagulating liquid synthetic resin, so that the case cover 24 and the case 2 are filled. A firm bond between is formed.

Case 2 sealed with a coagulating liquid synthetic resin
Two holes 44 are formed on the case cover 24 in order to let out the air generated when the inside is filled. A pair of holes 44 are provided symmetrically to each other and are provided in the chamber 38 so that the connecting portion 18 having a rectangular cross section and the chamber 38 are aligned. Here, the pair of holes 44 correspond to the sensor mounting portion 20 for mounting the sensor element 21, so that ambient air can circulate around the sensor element 21. In order to protect the sensor element 21 from the surrounding environment, which is contaminated, a filter 46 is attached to each of the two side surfaces corresponding to each hole 44, and each filter 46 is inserted into a groove 48 formed around 44. Is fixed. In this case, the filter 46 may be glued into the groove 48 with an adhesive.

The filter 46 is formed into a thin plate shape made of a usual synthetic material by using an injection molding technique. here,
The lamellae are formed by laminating Gore-tex fabric covered with thin film Teflon. The Teflon material is used to allow ambient air to be circulated around the sensor element 21, preferably using its ventilation performance during expansion. The synthetic material functions to prevent moisture from coming into contact with the sensor element 21 and allow gas to pass therethrough.

In addition, metal knitting or metal fabric is used as the outer layer of the filter 46 to block contact of the microplate with microparticles that adversely affect the performance of the microplate. The thin plate formed in the double layer is fixed in the groove 48, and the Teflon side faces the sensor element, while the metal knitting is provided along the edge portion of the chamber 38. Therefore, as shown in FIG. 4, when the case cap 50 is overlaid on the case cover 24, each metal knit is placed at a predetermined position.

In accordance with a preferred embodiment of the present invention, the thin plate filter may be embodied with conventional synthetic materials and metal braids, without the use of triple layer synthetic materials in particular. 4 and 5 show a case cap 5 of the gas detector according to the present invention.
Detailed sectional views and plan views for explaining the internal structure of No. 0 are shown, respectively. In FIG. 5, the maze-shaped air passage 5
2 is provided between the outer wall 54 and the inner wall 56 of the case cap 50. By forming the four slots 58a on the four side surfaces of the outer wall 54, the air is circulated through the maze-shaped air passage 52. Similarly, the inner wall 56 is provided with four slots 58b, each slot being offset from the slot 58a of the outer wall 54. For this purpose, first, the air that has passed through the slot 58a enters the slot 58b through the labyrinthine air passage 52, and subsequently the hole 44 and the filter 4 are inserted.
The sensor element 21 is reached via 6. Through such a flow of air, a sufficient insulating effect between the inside and the outside of the chamber 38 is obtained.

Therefore, even if the temperature change of the surrounding air is changed, the operating temperature of the sensor element 21 is kept constant, and the error operation of the sensor element 21 can be prevented. The connection between the outer wall 54 and the inner wall 56 is realized using a connecting frame. As shown by the broken line in FIG. 2, the case cover 2
The inner rectangle of 4 is aligned with the outer cross section of the chamber 38 so that the case cover 24 is rigidly mounted on the case 2. Further, as shown in FIG. 2, two stoppers 60 are provided.
Are provided in adjacent positions on both side surfaces of the chamber 38 in the width direction. As shown in FIG. 5, when the case cap 50 is placed on the case cover 24, the stoppers 60 are inserted into the labyrinth-shaped air passages 52 located in the width direction of the case cap 50, and the case cap 50 is inserted into the case cover 50. A protruding portion (not shown) formed in the case cap 50 when reaching a predetermined position on the 24.
By engaging with, a firm connection between the case cap 50 and the case cover 24 is obtained.

When assembling the gas detector of the present invention, the cable 12 is first inserted into the cable support member 14 and pulled out to the outside, and the circuit board 10 is side-guided to the stopper 16 provided on the bottom surface of the case 2. Mounted in case 2 along line 8. After that, case cover 2
4 is attached to the upper part of the case 2. Here, the flange 26 of the case cover 24 is firmly inserted into the case 2 until the edge portion 28 is aligned with the upper edge of the case 2.

Next, the case 2 has a hole 4 in the case cover 24.
It is filled with the coagulable liquid synthetic resin through any one of the two. In this case, the circuit board 10 and its elements are completely covered with the coagulating liquid synthetic resin, and the air existing in the case 2 escapes to the outside of the case 2 through the other 42 of the case cover 24. Further, the band 34 and the shielding member 30 are made to seal not only all the elements but also the case cover by the synthetic liquid synthetic resin. After the supplied coagulable liquid synthetic resin is solidified, the filter 46 is covered with the metal knitting described above, and the case cap 50 covers the case cover 24 until the stopper 60 of the case cover 24 engages with the protruding portion (not shown) of the case cap 50. It is inserted in 24. Thus, the assembly of the gas detection device of the present invention has been successfully completed so that the sensor element can be tested.

Although the preferred embodiments of the present invention have been described above, it goes without saying that various modifications can be made without departing from the scope of the claims of the present invention.

[0029]

Therefore, according to the present invention, it is possible to manufacture by a simpler assembling method, and it is possible to ventilate the ambient air by appropriately sensing harmful gas substances.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a gas detection device according to the present invention.

FIG. 2 is a detailed cross-sectional view of a case cover of the gas detection device according to the present invention.

FIG. 3 is a detailed plan view of a case cover of the gas detection device according to the present invention.

FIG. 4 is a detailed sectional view of a case cap of the gas detection device according to the present invention.

FIG. 5 is a detailed plan view of a case cap of the gas detection device according to the present invention.

[Explanation of symbols]

 2 Cases 4 and 6 Freight 8 Side guide wire 10 Circuit board 12 Cable 14 Cable support member 16, 60 Stopper 18 Connection part 20 Sensor mounting part 21 Sensor element 22 Conductive line 24 Case cover 26 Flange 28 Edge part 30 Shielding member 32 Recessed part 34 Bands 36, 40, 42, 44 Holes 38 Chamber 46 Filter 48 Groove 50 Case Cap 52 Maze-shaped Air Passage 54 Outer Wall 56 Inner Wall 58a, 58b Slot

Claims (12)

[Claims] 1. A gas detection device for use in a vehicle, which is capable of detecting harmful gas substances in the surroundings and appropriately circulating air around it, including a case to which a sensor element used in an electrical measuring device is attached. The sensor element comes into contact with the ambient air through an air passage, is attached to a connection portion of an electric circuit board, and protrudes from the case toward a chamber, and the chamber has a pair of holes and is on the case cover. And a corresponding set of filters is attached to the set of holes of the chamber, and the connecting portion is covered with a case cap having an air passage formed between an inner wall and an outer wall thereof. A gas detection device characterized by the following. 2. The case cover is attached to an upper part of the case, and in the chamber protruding from the case cover, the sensor element is horizontally provided on the chamber, and the two long side surfaces are provided with the sensor element. A gas detector according to claim 1, characterized in that it is designed such that a set of holes is provided. 3. A coagulating liquid to be filled in the case, wherein the chamber has a band that is slightly expanded inside the cover and is formed in a rectangular shape corresponding to the connection portion. The gas detection device according to claim 2, wherein the gas detection device is immersed in a synthetic resin. 4. The gas detection device according to claim 3, wherein a shielding member is provided between the band and the connecting portion. 5. The flange according to claim 3, wherein the case cover is provided with a flange formed along an edge portion thereof, the flange being inserted into the case and firmly fixed to an upper inner wall of the case. Gas detector. 6. The gas detection device according to claim 1, wherein the pair of holes are formed on two side surfaces of the chamber of the case cover. 7. The filter is made of a thin sheet GORE-TEX fabric and has tetrafluoroethylene (Tetrafluore).
6. The gas detection device according to claim 1, wherein the gas detection device is coated with a thin film synthetic resin material that allows a gas such as styrene to pass therethrough. 8. The gas detection device according to claim 1, wherein the outer side of the thin plate filter is covered with a metal braid. 9. The gas detection device according to claim 1, wherein the case cap is formed in a double layer having a plurality of slots arranged in a zigzag pattern. 10. The chamber and the case cap are each formed in a rectangular shape, the case has four outer walls each having one slot, and the two longitudinal sides of the inner wall each have two slots. The gas detection device according to claim 9, wherein 11. A pair of slots are formed adjacent to two lateral sides of the chamber, and each slot is inserted into a gap formed between the inner wall and the outer wall of the case cap. The gas detection device according to claim 10, wherein: 12. The gas detection device according to claim 1, wherein the sensor element is a metal oxide sensor such as a zinc oxide sensor.